Experimental Study on Drilling Performance of Bio-Waste-Based Corn Husk Fiber Reinforced Epoxy Composites for Green Applications

This study focuses on the machinability optimization of bio-waste corn husk fiber–reinforced epoxy composites during drilling, with the objective of minimizing delamination and improving hole quality required for mechanical fastening applications. While natural fiber composites have been widely investigated, systematic statistical optimization of drilling parameters for corn husk fiber composites remains limited. The novelty of this work lies in identifying the dominant drilling parameter and establishing a clear damage-control strategy using a Taguchi L16 design coupled with ANOVA. Drilling experiments were conducted by varying spindle speed (1000, 1500, 2000, and 2500 rpm), drill diameter (6, 8, 10, and 12 mm), feed rate (00.05, 0.10, 0.15, and 0.20 mm/rev), and point angle (90°, 100°, 110°, and 120°). The results show that the drill diameter is the governing factor affecting delamination, contributing 73.52% of the total variation, followed by spindle speed (22.68%), whereas feed rate (3.14%) and point angle (0.38%) have minimal influence. The optimal condition (2500 rpm, 6 mm drill diameter, and 0.05 mm/rev feed rate) produced the lowest delamination and improved surface integrity. Microscopic observations confirmed reduced fiber pull-out and matrix cracking under these conditions. The main advantage of the proposed approach is the clear identification of parameter priority, enabling the industry to control drilling damage by primarily selecting appropriate drill diameter and spindle speed. The findings provide practical machining guidelines for the use of corn husk fiber composites in lightweight panels, automotive interior parts, and secondary structural components where reliable bolted joints are required.